Two summers ago there were only 29 women in the world better at tennis than Zhang Shuai, the Chinese qualifier who will face Britain’s Johanna Konta in the last eight of the Australian Open. Zhang reached her career-high ranking on 7 July 2014, shortly after a tenacious run to the last four on the grass courts of Edgbaston. It was her third semi-final that year and it came barely a month after she had made the quarter-finals in Rome. Life was good.

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Yet 18 months on, at an age when most athletes are approaching their prime, the 27-year-old from Tianjin touched down in Melbourne with friends and family in tow and retirement on her mind. After failing to maintain her rise Zhang’s ranking had slumped to No133 and she was struggling to make ends meet.

Where did it all go wrong? Well, Zhang’s was always a singular success. One would expect a player ranked as high as No30 to have caused the odd ripple at grand slam level. Kristina Mladenovic, the Frenchwoman who currently occupies that berth, has reached the third round or better at all four grand slam tournaments while Sloane Stephens, the Floridian who ended last year in 30th spot, is a former Melbourne semi-finalist and a member of Wimbledon’s last-eight club. Zhang is different: before the start of what has snowballed into a fairytale campaign in Australia she had played 14 majors without registering a victory.

That she has belatedly hit on a winning formula is perhaps testament to the virtues of contesting every match as though it were her last. In other circumstances an opening round that pitted the Chinese qualifier against Simona Halep might well have been just that. But the combination of an achilles tendon injury and a cold meant the Romanian second seed came into the tournament undercooked. With three qualifying matches behind her the same could not be said for Zhang, who took full advantage, beating Halep in straight sets to break her grand slam duck.

That victory left Zhang and her coach, Liu Shuo, in tears, but Zhang’s form continued on an upward trajectory with a second-round victory over Alizé Cornet, the 33rd-ranked Frenchwoman who completed her Australian Open preparations by winning the warm-up event in Hobart. Cornet has often flattered to deceive since gracing the front cover of L’Equipe as a teenager but she is a gifted player whom Zhang had failed to beat on three previous occasions.

Her confidence burgeoning, Zhang went on to dispatch the naturalised American Varvara Lepchenko 6-1, 6-3, blasting an impressive 27 winners along the way. But one does not come from nowhere to reach the last eight of a major without some good fortune along the way. For that Zhang – a popular figure whose success has been the toast of her peers – has been relying on a “lucky locker” once used by her compatriot Zheng Jie, a semi-finalist in 2010.

“Zheng Jie, she always very lucky, she play well in Australian Open,” said Zhang in her engaging broken English after beating Lepchenko. “But this year she didn’t come. This year I use her lucky locker. I don’t remember the locker number but she said, ‘OK, I give you my lucky locker. I hope you can [be] lucky this year.’ So I think from her a lot lucky this year.”

An injured opponent tends to be a more reliable source of good luck, however, and – as she later conceded – the gods seemed to smile on Zhang against the powerful American Madison Keys. For 32 minutes, the time it took Keys to lock up the first set 6-3, a seventh match in 10 days looked one too many for the Chinese. Zhang was struggling to deal with her opponent’s superior weight of shot before Keys, who reached the semi-finals in Melbourne last year, pulled up with a hip injury three games into the second set.

Nonetheless, when Konta and her camp scrutinise the match there are clear lessons to be learned. Both players will be contesting the quarter-final of a major for the first time, of course, and with their head-to-head record tied at one win apiece there will doubtless be nerves on both sides. But if Keys’ early success is a reliable guide, Konta’s big serve and all-court aggression should stand her in good stead.

Whatever the outcome, it would be a shame if Zhang were to call it a day now. Her performances in Melbourne suggest she could yet ruffle a few feathers with her pancake-flat groundstrokes, scampering movement and occasionally deft touch. Rest rather than retirement is apparently now the plan.

“Right now, after this tournament, I need a long break,” said Zhang after beating Keys.

“I’ve already played seven matches. Before today I was thinking, ‘OK, today is the final.’ When somebody wins six matches at a grand slam, it’s already the final, right? And at night it felt like it.

“But I’d already said this year I’ll play less tournaments. I don’t want to play too much. I want some more time for my life. I can have a holiday, rest, stay with my parents – and practise more too.”